Traditionally, operating systems have provided a number of abstract internal interfaces which have been designed to support the various families of hardware devices connected to the system; for example, storage, networking, graphics. Operating systems typically also provide a driver model which enables bespoke hardware to be connected which does not fit a standard driver model. In the current Microsoft Windows implementation the network model is called NDIS and the generic driver model is called WDM. Implementation rules state that an NDIS device driver should not directly interact with a WDM driver. This is also good engineering practice.
Typical network interface devices do not support NDIS as a vertical (peer) interface to WDM. Thus, for instance, the IETF RDMA consortium and the Infiniband architectures are not defined with a vertically separated structure. An example of such an architecture is shown in FIG. 1. This architecture presents difficulties in supporting both standard kernel based network services at the same time as application-level network services and invites the layering of functionality: for example, building NDIS driver functionality above the Kernel AGENT or as part of the kernel AGENT.
It has been proposed to provide a network interface that presents a user-level network interface with a driver architecture which supports (a) a protected control interface which is accessible from user level transport libraries and (b) a standard network driver interface. In the past, such an architecture has been realised by layering such an interface (b) on top of such an interface (a). This approach has the advantage that it is relatively easy to pass messages between the drivers. However, this approach is inefficient, especially in the Windows architecture, and it has the disadvantage that both divers must be loaded in order for the interface (b) to be operated and that interface (a) must expose an upper layer API for (b) as well as a control API for user level transport libraries.
According to the present invention there is provided apparatus and methods as set out in the accompanying claims.